Originally Posted by Glenn E. Meyer
Do the laws specifically mention mags - yes, I could look that up but I'm not in the mood?
No, the law does not mention anything about firearms accessories that may be illegal in that state, only the firearm itself. It also tells you how to transport ammo with the firearm, but makes no mention of any other firearm part or accessory.
18 USC 926a:
§ 926A. Interstate transportation of firearms
Notwithstanding any other provision of any law or any rule or regulation of a State or any political subdivision thereof, any person who is not otherwise prohibited by this chapter from transporting, shipping, or receiving a firearm
shall be entitled to transport a firearm
for any lawful purpose from any place where he may lawfully possess and carry such firearm
to any other place where he may lawfully possess and carry such firearm
if, during such transportation the firearm is unloaded, and neither the firearm nor any ammunition being transported is readily accessible or is directly accessible from the passenger compartment of such transporting vehicle: Provided, That in the case of a vehicle without a compartment separate from the driver’s compartment the firearm or ammunition shall be contained in a locked container other than the glove compartment or console.